Radiotherapy in colon cancer is used in two uncommon scenarios:

  • When the tumour is stage T4b (high risk of local recurrence and improvement in local control on case series compared to surgery alone)
  • When there are oligometastases that are not resectable surgically (yet the primary is)

Adjuvant Radiotherapy for T4b disease


  • Informed Consent
  • Other specialists: Medical oncologist (for concurrent chemotherapy), surgeon and pathologist (to determine exact site of disease extent)
  • Allied Health: Dietician


  • Position: Prone, or decubitus (may help shift small bowel away from treatment site
  • Immobilisation: Wingboard with arms raised. May need vacuum bag if decubitis position used.
  • Bolus: Not required
  • CT: From carina to greater trochanter
  • 4D CT: Not usually indicated


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